I think that 25K is tops for a car that needs restoring. In this case both buyer and seller should be content that a good deal was struck.
Emphasis added on "should be" particularly for the seller. However you may be surprised, or maybe not; there's this "halo" around the three point star, and a lot of those who find themselves in possession of a tired and worn old Mercedes--a Pagoda in particular--will place unrealistic value on it due to both their ignorance of what it takes to bring it back to life, and this imaginary "halo". Their guidepost is the minuscule amount of research they've done on cars that have sold, and they seemingly dismiss the difference between a running car and a junker.
Back in 2012, I paid a visit on behalf of [well known early member] Pete Lesler to a 230SL that he had gotten a lead on. It was in a barn--a real barn, NOT a garage--up a two-track path. The car had belonged to the woman's father, and had been sitting untouched for
decades. Nearly everything on the car organic was gone; disintegrated from age and rodents. I found very little salvageable on the hulk; nothing could be used without major restoration or replacement. Even simply removing the car to daylight, and then to a tow-truck would have required dragging it out of the barn with a small tractor down to the road where it could then be placed on a flatbed. We've seen cars like this, like the one pulled out of the Neckar River (OK, that was worse...). In reviewing the car for Pete I took a lot of photos and had him on the phone as I looked at it on his behalf. Fresh in my mind was the 1,000+ hours of labor and at least $50K in parts it took to restore mine 1999-2001. The challenge was the woman who owned it was one of those smitten by the halo and the promise of a windfall because it was a Pagoda.
She was adamant that it was worth $15K and wasn't willing to discuss anything lower. Remember this was 2012, before the days of six-figure Pagodas. I don't know what ever happened to it, if anything, but it carried the VIN 113.042-10-00072 making it an early 230SL. Maybe it's still in the barn in Southfield, MI.
(N.B. I have the photos in a folder on my computer titled "Crappy old Pagoda for Pete")